On 30 July 2015 Teiron Jones and Erka Xu sent off for a fishing trip on a relatively benign mid-winter's morning.

But after deciding to return early, Jones, 60, chose a poor time to cross the Waitara bar and the boat capsized, throwing both men into the water.

A surfer rescued Jones, but his 52-year-old friend was drowned.

Neither man was wearing a lifejacket, breaching maritime rules that require them to be available and worn when crossing a bar.

The Crown argued Jones had failed to take all necessary safety precautions required by law by not having lifejackets on board.

Justice Williams told the court the case was unusual because it was the first time a manslaughter prosecution had been brought for a breach of Maritime rules.

Jones' defence lawyer Ron Mansfield had sought a discharge without conviction, but Justice Williams said a conviction was appropriate.

"Mr Xu drowned on your watch. You put him in harm's way by crossing that bar at a problematic time without the necessary safety equipment.

"You are responsible for putting both him and you in a situation where even the slightest mistake would have the most serious of consequences.

"I consider public acknowledgement of those facts through the entry of a conviction is a proportionate response to that reality."

Justice Williams acknowledged Jones had a pre-existing head injury that affected his decision-making and made him prone to panic.

He also praised his actions as the drama unfolded.

"You immediately moved to help Mr Xu. You carried the only floatation device available on the craft to him and you ensured that he was as safe as he could be before you returned to the inevitably hopeless task of pursuing the boat.

"In short you did what you could in the circumstances."

Earlier Mr Xu's widow's victim impact statement was read out in which Huijing Hou relived the moment she found out her husband was dead.

"I heard (my sister) Jenny scream over the phone. Jenny told me he was gone. I could not believe it even after a policeman allowed me to see his body.

"He was alive when he departed in the morning. In shock my head go empty."

Ms Hou said although she and her daughter felt the pain of her husband's loss every day, she had forgiven Jones.

"Teiron is lucky to be alive and I do not want him to be tortured by what happened to my deceased husband."

At the conclusion of the sentencing Justice Williams allowed Jones, a 60-year-old music teacher, to make a statement of his own.

"I've lost my friend and I grieve everyday and every time I look upon the water I remember and the first thing I do in the morning when I wake up is I remember.

"I accept full responsibility for what happened and I have the deepest regret that words cannot explain."

Jones was convicted and discharged and ordered to pay $5000 in reparations.

In a statement, Maritime New Zealand said the conviction sent a strong and tragic reminder to all recreational boaties to follow basic safety practices -- in particular wearing lifejackets.